1. Field of the Invention
The present invention relates to a liquid-encapsulated damper mount for supporting an upper portion of a damper for suspending a wheel of an automobile on a vehicle body.
The present invention also relates to a mounting structure for mounting a hydraulic damper used in a suspension of an automobile to a vehicle body, and particularly to a hydraulic damper mounting structure for mounting an upper portion of a hydraulic damper to a vehicle body with an anti-vibration rubber member interposed therebetween.
2. Description of the Related Art
One example of a conventional damper mount M for an automobile is shown in FIG. 18. This damper mount M is adapted to support an upper end of a hydraulic damper 11 for reducing a load input from a wheel in an opening 12a in a vehicle body 12 (on an upper wall of a wheel house), and includes a cylindrical damper case 13 in which a hydraulic cylinder is accommodated, and a damper rod 14 which is connected to a piston slidably received in the hydraulic cylinder and protrudes from an upper surface of the damper case 13 for sinking movement into the damper case 13. The damper rod 14 has a larger-diameter portion 14a and a smaller-diameter portion 14b from a side closer to the damper case 13, and an externally threaded portion 14c formed around an outer periphery of a tip end of the smaller-diameter portion 14b. A washer 15, a cup-shaped first bracket 16 with its lower surface opened, a collar 17 and a washer 18 are fitted above a step between the larger-diameter and smaller-diameter portions 14a and 14b and fastened by a nut 19 threadedly fitted over the externally threaded portion 14c. 
A bump stopper 20 formed of an elastic member around an outer periphery of the larger-diameter portion 14a below the washer 15 is fitted within the first bracket 16 and has a lower surface opposed to an upper surface of the damper case 13 with a predetermined clearance provided therebetween. Therefore, when a large load is input to the wheel to retract the damper rod 14 largely into the damper case 13, the maximum amount of contraction of the hydraulic damper 11 can be restricted by the abutment of the upper surface of the damper case 13 against the lower surface of the bump stopper 20. A disk-shaped second bracket 21 having an opening 21a surround the periphery of the damper rod 14 is fixed to the periphery of the opening 12a in the vehicle body 12 by a plurality of bolts 22, and a suspension spring 24 is supported at its upper end on a spring seat 23 mounted to an outer periphery of a lower surface of the second bracket 21. A ring-shaped lower elastic member 25 is supported between the lower surface of the second bracket 21 and an upper surface of the first bracket 16, and a ring-shaped upper elastic member 26 is supported between an upper surface of the second bracket 21 and a lower surface of the washer 18.
Therefore, when a load is input from the wheel, a damping force is generated by the lower elastic member 25 and the upper elastic member 26 in addition to a damping force of the hydraulic damper 11 itself, and further, the inclination of an axis of the hydraulic damper 11 caused with the movement of the wheel can be absorbed by the resilient deformation of the lower and upper elastic members 25 and 26.
Another example of a conventional damper mount M for an automobile is shown in FIG. 19. Members or portions corresponding to those in the damper mount M described with reference to FIG. 18 are designated by like reference characters, and the duplicated description is omitted.
This damper mount M adopts a liquid-encapsulated structure in order to provide a damping force larger than that of the damper mount M described with reference to FIG. 18. More specifically, inner and outer peripheral surfaces of a block-shaped elastic member 27 are bonded by vulcanization to an outer peripheral surface of a collar 17 and an inner peripheral surface of a second bracket 21, respectively, and a lower surface of the elastic member 27 is supported on an upper surface of a first bracket 16. Outer peripheries of a partition plate 28, a diaphragm 29, a diaphragm holder 30 and a cap 31 are superposed in an opening 21b in the second bracket 21, and the outer periphery of the cap 31 is caulked to the second bracket 21, whereby the second bracket 21, the partition plate 28, the diaphragm 29 and diaphragm holder 30 and the cap 31 are coupled integrally to one another.
A first liquid chamber 32 having an operating liquid encapsulated therein is defined by the elastic member 27, the second bracket 21 and the partition plate 28, and a second liquid chamber 33 having an operating liquid encapsulated therein is defined by the partition plate 28 and the diaphragm 29. The first and second liquid chambers 32 and 33 communicate with each other through a communication passage 28a defined in the partition plate 28. Ethylene glycol, viscous silicone oil or the like is used as the operating liquid.
Therefore, when a load is input from a wheel, a damping force is generated by the elastic member 27 in addition to a damping force of the hydraulic damper 11 itself, and further, a damping force is exhibited by the operating liquid passed through the communication passage 28a. More specifically, when a damper rod 14 is offset upwards, causing the elastic member 27 to be compressed and deformed, the volume of the first liquid chamber 32 is decreased. Therefore, the operating liquid forced out of the first liquid chamber 32 is passed through the communication passage 28a into the second liquid chamber 33 to expand the diaphragm 29. On the other hand, when the damper rod 14 is offset downwards, causing the elastic member 27 to be pulled and deformed, the volume of the first liquid chamber 32 is increased. Therefore, the diaphragm 29 of the second liquid chamber 33 is shrunk due to vacuum, whereby the operating liquid is passed through the communication passage 28a and drawn into the first liquid chamber 32. In this manner, the operating liquid in the first liquid chamber 32 and the second liquid chamber 33 is passed through the communication passage 28a alternately between the first liquid chamber 32 and the second liquid chamber 33 with the vertical movement of the damper rod 14, and at this time, the damping force is generated.
The conventional liquid-encapsulated damper mount M described with reference to FIG. 19 suffers from the following problem: The first liquid chamber 32, the partition plate 28, the second liquid chamber 33, the diaphragm 29 and the cap 31 are disposed above the upper end of the damper rod 14 and for this reason, the vertical size of the damper mount M is increased, and also these members are passed through the vehicle body 12 (the upper wall of the wheel house) to protrude largely into an engine room.
In an automobile or the like in general, a suspension as shown in FIG. 20 is provided in order to receive a load applied between a vehicle body and a wheel and to moderate the shock transmitted from a wheel to a vehicle body to improve the riding comfort. FIG. 20 is a perspective view showing a suspension S on a front side. The suspension S usually comprises a knuckle 102 supporting an axle, an upper arm 103 coupled to the knuckle 102 and connected to a wheel house on the vehicle body, a lower arm 104 coupled to the knuckle 102 and connected to a sub-frame on the vehicle body, a hydraulic damper 106 as a damper coupled to the lower arm 104 by a damper fork and mounted at its upper portion to an upper portion of the wheel house by bolts 108 through a damper mount 107 (the detail of which will be described hereinafter), and a coil spring 109 disposed to surround a periphery of the hydraulic damper 106 and adapted to support a load of the vehicle body together with the hydraulic damper 106.
Not only a vertical load based on the weight of the vehicle body is applied to the suspension S, but also a lateral load is applied to the suspension S in accordance with a steering force during turning movement of the vehicle or a state of a road or in accordance with an operational state of the automobile during turning movement, acceleration or braking of the automobile. A measure is taken so that the lateral load is received by each of the upper and lower arms 103 and 104, whereby the influence of the lateral load to the hydraulic damper 106 is possibly reduced. The hydraulic damper 106 is generally formed as a strut-type long member extending in a lengthwise direction (an axial direction). The hydraulic damper 106 is adapted to absorb a shock mainly from a road surface by a damping effect provide by an internal hydraulic pressure in response with the expansion or contraction of a strut to inhibit the vibration of the vehicle. The hydraulic damper 106 is mounted to the wheel house through the damper mount 107 and hence, the transmission of a high-frequency vibration from the road surface to the vehicle body is cut off.
FIGS. 21 and 22 show conventional structures of mounting of the upper portion of the hydraulic damper 106 to the wheel house which is a structure on the vehicle body. The conventional mounting structure 180 shown in FIG. 21 uses a damper mount 185 including an anti-vibration rubber member bonded by vulcanization. A larger-diameter portion 112, a step 113 and a smaller-diameter portion 114 are formed on a piston rod 111 protruding on the upper portion of the hydraulic damper 106 in the named order towards a tip end of the piston rod 111, and an externally threaded portion 115 is formed at a foremost tip end of the piston rod 111. A locking member 116 made of a steel material is fitted over the smaller-diameter portion 114, so that it is seated on a step 113. A bump stopper 118 fitted over the larger-diameter portion 112 and adhered to the locking member 116 is disposed between the locking member 116 and an upper surface 117 of a cylinder 106a of the hydraulic damper 106 with a clearance defined between the bump stopper 118 and the upper surface 117 of the cylinder. When the hydraulic damper 106 is contracted excessively, the upper surface 117 of the cylinder is put into abutment against the bump stopper 118, thereby dampening an excessive load. An outer periphery of the bump stopper 118 is covered with a tubular dust cover 119 with only its lower portion opened.
The damper mount 185 is comprised of a collar 186 fitted over the smaller-diameter portion 114 of the piston rod 111, a mounting plate (a base plate) 187 mounted to the wheel house by screwing a mounting bolt 108 into the wheel house on the vehicle body, and an anti-vibration rubber member 189 disposed and bonded by vulcanization between an outer peripheral surface of the collar 186 and an inner peripheral surface of a folded-back portion 188 of the mounting plate 187. The damper mount 185 is assembled to the hydraulic damper 106 by screwing a nut 123 over the externally threaded portion 115 of the piston rod 111 having the collar 186 fitted thereover and clamping the anti-vibration rubber member 189 between a retaining plate 122 and a top surface 120 of the dust cover 119. The anti-vibration rubber member 189 of the damper mount 185 is curved in its section to come into close contact with the folded-back portion 188 and hence, can transmit not only a load in an axial direction of the hydraulic damper 106 but also a load in a radial direction perpendicular to the piston rod 111. The anti-vibration rubber member 189 is of a vulcanization-bonded type and has a stable characteristic and hence, such a damper mount 185 is used mainly for a high-grade automobile.
The conventional mounting structure 190 shown in FIG. 22 uses a damper mount 195 having an anti-vibration rubber member which is not bonded by vulcanization. The structure of a hydraulic damper 106 is similar to the structure shown in FIG. 21 and hence, like components and portions are designated by a like reference characters and the duplicated description is omitted. The structure on the side of a vehicle body comprises a first mounting plate 196 clamped to a wheel house by mounting bolts 108, and a second mounting plate 197 superposed on the first mounting plate 196. The first mounting plate 196 comprises a curved portion 196a and a flat portion 196b extending inwards from the curved portion 196a. The second mounting plate 197 comprises a curved portion 197a and a flat portion 197b, which are of shapes symmetric with the curved portion 196a and the flat portion 196b of the first mounting plate 196.
The damper mount 195 comprises a first anti-vibration rubber member 198 mounted between the top surface 120 of the dust cover 119 and the first mounting plate 196, and a second anti-vibration rubber member 199 mounted between the retaining plate 122 and the second mounting plate 197. The anti-vibration rubber members 198 and 199 are umbrella-shaped rubber members disposed to surround the outer periphery of the collar 186, so that their opened sides are opposed to each other. An annular portion of each of the anti-vibration rubber members 198 and 199 is of a substantially egg-shape in section, so that an inner peripheral edge corresponding to a pointed end abuts against a corner formed between the collar 186 and the top surface 120 of the dust cover or the retaining plate 122, and an outer peripheral edge corresponding to a rounded end abuts against the curved portion 196a of the first mounting plate 196 or the curved portion 197a of the second mounting plate 197.
The damper mount 195 is assembled to the hydraulic damper 106 by screwing a nut 123 over the externally threaded portion 115 of the piston rod 111 having the collar 186 fitted thereover and clamping the anti-vibration rubber members 198 and 199 between the retaining plate 122 and the dust cover 119. The anti-vibration rubber members 198 and 199 of the damper mount 195 are in close contact with the curved portions 196a and 197a (each curved in section) of the first and second mounting plates 196 and 197 and hence, can transmit not only a load in an axial direction of the hydraulic damper 106 but also a load in a radial direction perpendicular to the piston rod 111. The anti-vibration rubber members 198 and 199 are not bonded by vulcanization to any of the first mounting plate 196, the second mounting plate 197, the collar 186 and the dust cover 119 and are produced at a low cost and hence, such a damper mount 195 is used for a standard automobile.
Desired functions provided by the damper mount are a function of maintaining the position of the hydraulic damper in the axial direction of the hydraulic damper, i.e., a substantially vertical direction, and a direction perpendicular to the axis of the hydraulic damper, i.e., in a lateral direction and a longitudinal direction, a function of permitting the oscillating movement of the hydraulic damper relative to the vehicle body, and an anti-vibration function against the input of vibration in all these directions. The mounting structures shown in FIGS. 21 and 22 are designed so that these functions can be satisfied. For example, the maintaining function in the direction perpendicular to the axis exerted by the vulcanization-bonded type damper mount 185 shown in FIG. 21 is provided at a portion of the anti-vibration rubber member having an axial thickness of the folded-back portion 188 of the mounting plate 187. Therefore, the regulation of the maintaining function is performed by regulating the axial thickness of the folded-back portion 188. The damper mount 195, which is not of the vulcanization-bonded type and which is shown in FIG. 22, has a maintaining function in the direction perpendicular to the axial direction, which is provided by regulating the opening angles of the umbrella-shaped anti-vibration rubber members 198 and 199.
However, any of these structures suffer from the following problem: The maintaining function in the longitudinal and lateral direction which is the direction perpendicular to the axis of the hydraulic damper is obtained above the hydraulic damper. For this reason, it is difficult to reduce the length of the entire damper assembly including the hydraulic damper and the damper mount, i.e., the height of the entire damper assembly in a state in which it has been applied to the automobile.
Accordingly, it is an object of the present invention to reduce the vertical size of the damper mount.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided a liquid-encapsulated damper mount for supporting an upper portion of a damper for suspending a wheel of an automobile on a vehicle body, comprising an elastic member connecting a bracket fixed to the vehicle body to the upper portion of the damper, a first liquid chamber defined at least in part by the elastic member, a second liquid chamber defined at least in part by a diaphragm, and a communication passage permitting the first and second liquid chambers to communicate with each other, wherein the elastic member is formed into a tubular shape to surround an outer periphery of the upper portion of the damper so that it is shear-deformed vertically with the vertical movement of the damper relative to the bracket fixed to the vehicle body, to thereby increase and decrease the volume of the first liquid chamber.
With the above arrangement, the elastic member connecting the bracket on the vehicle body to the upper portion of the damper is formed into the tubular shape to surround the outer periphery of the upper portion of the damper so that it is shear-deformed vertically with the vertical movement of the damper to change the volume of the first liquid chamber. Therefore, it is possible to reduce the vertical size of the damper mount, while ensuring a large amount of change of the volume of the first liquid chamber, as compared with the conventional damper mount in which the block-shaped elastic member mounted at the upper portion of the damper can be deformed in a compressed and pulled manner to change the volume of the first liquid chamber.
According to a second aspect and feature of the present invention, in addition to the first feature, the diaphragm is located below the elastic member and inside a suspension spring placed around an outer periphery of the damper.
With the above arrangement, the diaphragm is located below the elastic member and hence, the volume of the second liquid chamber defined by the diaphragm can be ensured at a large value. In addition, the diaphragm is located inside the suspension spring and hence, when the damper is assembled to the vehicle body, it is difficult to damage the diaphragm by a tool or the like.
According to a third aspect and feature of the present invention, there is provided a structure for mounting a hydraulic damper used in a suspension of an automobile on a vehicle body, comprising a first rubber member disposed between an axial end of the hydraulic damper and the vehicle body and adapted to receive a load in an axial direction of the hydraulic damper, and a second rubber member disposed between an outer peripheral portion of the hydraulic damper and the vehicle body and adapted to receive a load in a radial direction perpendicular to an axis of the hydraulic damper.
With the above arrangement, a maintaining function in the axial direction of the damper mount and a maintaining function in a direction perpendicular to the axis are separated in the structure of mounting of the hydraulic damper on the vehicle body. Therefore, the first rubber member disposed between the axial end of the hydraulic damper and the vehicle body receives a load in the axial direction of the hydraulic damper and exhibits the maintaining function in the axial direction of the damper mount, and the second rubber member disposed between the outer peripheral portion of the hydraulic damper and the vehicle body receives a load in the radial direction perpendicular to the axis and exhibits a maintaining function in the radial direction sideways of the hydraulic damper. Therefore, The distance between the axial end of the hydraulic damper and the vehicle body is a length only corresponding to the thickness of the first rubber member, and the length of the entire damper assembly can be shortened.
According to a fourth aspect and feature of the present invention, there is provided a structure for mounting a hydraulic damper used in a suspension of an automobile on a vehicle body, comprising a first rubber portion disposed between an axial end of the hydraulic damper and the vehicle body and adapted to receive a load in an axial direction of the hydraulic damper, and a second rubber portion disposed between an outer peripheral portion of the hydraulic damper and the vehicle body and adapted to receive a load in a radial direction perpendicular to an axis of the hydraulic damper, wherein the first and second rubber portions are formed integrally with each other.
With the above arrangement, the first and second rubber members are formed integrally with each other and hence, the number of parts can be reduced, leading to a reduction in cost, and the handling of the anti-vibration rubber members is facilitated during assembling and positioning thereof.
According to a fifth aspect and feature of the present invention, in addition to the third feature, a clearance is defined between the outer peripheral portion of the hydraulic damper and the second rubber member.
With the above arrangement, the clearance is defined between the outer peripheral portion of the hydraulic damper and the second rubber member. In those instances when the hydraulic damper receives a load in the radially inward direction intersecting the axial direction, the radially inward displacement of the hydraulic damper is equal to or smaller than the clearance, when the load is small, as is a road noise. Therefore, the load is not transmitted to the vehicle body because of the clearance, to provide a vibration-insulating state.
According to a sixth aspect and feature of the present invention, in addition to the third feature, the first and second rubber members are retained in such a manner that they are sandwiched between the hydraulic damper and the vehicle body.
With the above arrangement, the first and second rubber members are retained in such a manner that they are sandwiched between the hydraulic damper and the vehicle body and hence, the working of members for the vehicle body can be carried out in advance, and the mounting of the hydraulic damper can be achieved easily.
A hydraulic damper 11 in each of first to fifth embodiments corresponds to the damper of the present invention; a second bracket 52 in each of first to fifth embodiments corresponds to the bracket of the present invention; and a second elastic member 56 in each of first to fifth embodiments corresponds to the elastic member of the present invention.
The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.